This invention relates to dialyzers, the purpose of which is well known in medical and research organizations. One common use for a dialyzer is to reduce, for example, the salt concentration of a carrier liquid in a sample to be dialyzed without a substantial increase in the volume of the carrier liquid. The salt concentration could be reduced by dilution; however, this would proportionately increase the volume of the carrier liquid.
For example, a sample to be dialyzed contains a protein in a high saline solution, and it is desired to reduce the concentration of the salt in the saline solution. The sample is placed in a small container which is semi-permeable. The sample container is then placed in a much larger vessel which contains a liquid of very low salt concentration.
The dialyzer is configured in a manner such that when the sample container is placed in the dialyzer, the semi-permeable container separates the liquid in the sample container from the larger volume of liquid with which the sample is to dialyze. The material from which the sample container is made must be of such porosity as will permit diffusion or passage of the salts through the container, while at the same time barring passage of the protein.
The greater the ratio between the two volumes of the liquids, the greater will be the reduction of the salt concentration in the sample. For example, if the volume of the liquid in the dialyzer is 1000 times greater than the volume of the liquid in the sample, nearly all the salt can be removed from the sample to make the sample nearly salt-free.
The dialysis process is greatly accelerated by agitating or stirring both liquids. With past dialyzers it has not been too difficult to provide mechanisms for stirring the large volume of liquid in the dialyzer; however, there has remained the problem of simultaneously agitating the sample in a manner such that there is relative motion of the liquids on opposing sides of the sample container.
The conventional method for dialyzing small samples in a laboratory has been to place the sample into a commercially available dialysis tubing which is semi-permeable material. The lower end of the tube is closed by tying a knot in the tubing, and after the smple has been placed in the tubing, the upper end of the tubing is closed with a second knot.
The small tubes containing the samples are then immersed in the surrounding liquid in the large container of the dialyzer where they are preferably tied to the container by strings in order that they are not swept along with the water current as the water is stirred to wash away the salt diffusing from the samples in the tubes. Obviously, the mixing of the samples inside the tubes is far less than that of the liquid outside of the tubes, although the agitation of the samples in the tubes is of comparable importance. One of the chief disadvantages of the conventional method is the time consumed in preparing for the dialysis operation. Time saving arrangements thus far have been developed only for large volume single-sample dialysis as used in manufacturing operations.
As will be depicted and described below, the applicants have invented an apparatus and method for the dialysis of either a single small sample, or the dialysis of multiple small samples, which is far more expeditious and cost efficient than all prior known methods.